"We're fairly confident that the data we've seen from monitoring the area demonstrates the air quality in the region is meeting acceptable standards," said Neil Shelly of the Heartland Industrial Association, which represents 40 companies clustered in the 800-square- kilometre region.
An Alberta Environment spokeswoman said the air is closely monitored by a local agency and cases where guidelines for toxic chemicals are exceeded are extremely rare.
Nikki Booth said that levels of benzene — one of the chemicals being emitted and a known carcinogen — only exceeded one-hour guidelines once in 2012 and not at all in 2011. She said the average annual benzene level was below guidelines in both years.
But a woman who helped conduct the research points out that her Nobel-Prize-winning lab has been to the region three times between 2008 and 2012 and recorded similar results each visit.
University of California scientist Isobel Simpson, co-author of a paper released Wednesday, concluded air downwind from what is called the Industrial Heartland contains pollutants at levels equal to some of the world's largest cities. Other pollutants, including some known to cause cancer, also measured well above background levels.
Although the paper doesn't draw a cause-and-effect relationship, the research found rates of cancers linked to those chemicals were higher in communities closest to the stacks.
New Democrat MLA Rachel Notley said the doubt being cast on the study sounds like a script she's heard before.
"Step one of the playbook is undermine the credibility of the people that raise the concerns and do that for a long time," she said. "We're back at step one again."
Air quality in the region has been monitored since 2003 by the Fort Air Partnership, which is funded by government and industry. A private consultant hired by the group to review its work in 2012 gave it high marks.
Director Nadine Blaney said the group's monitoring is designed to see if air quality meets standards.
"What we monitor for is regulated by the government of Alberta. They are mandating what we monitor."
Simpson said that may not be enough. She said the effect of benzene, conclusively linked to blood cancers such as leukemia, seems to be cumulative and that even small doses are dangerous over long times.
The World Health Organization says there is no safe level for benzene.
Shelly said Heartland facilities are new by industry standards and are regularly audited to see if they're using the latest technology. He suggested that if emissions meet government standards, resources might be better allocated elsewhere.
"Is there a concern with the air quality in the region and does that warrant continual investments in one type of pollution control?"
He suggested that the reputation of Simpson's lab doesn't necessarily mean its data meets Alberta standards.
"To jump to the conclusion that (because) they have an international reputation means they followed all the protocols is quite a big jump."
Simpson said her lab has specialized in air monitoring for 30 years and has worked in 75 cities around the world. It regularly supplies data to agencies such as NASA.
"It's not the first time we've been attacked for saying something unpopular," she said.
Notley said a better response would be to take the results of Simpson's paper to heart.
"We should be reviewing our allowable air quality limits. And then we should be reviewing more aggressively whether we're meeting them."
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